Supported metal salt/phosphine complexes and metallized products therefrom

ABSTRACT

Metal salt/phosphine complexes deposited within and/or on a metallic or nonmetallic support or substrate, said complexes being derived from one mole of a nonorganometallic salt of a normally solid heavy metal of the Deming Periodic Table, for example, gold or palladium chloride, and 1 to 4 moles of a triorganophosphine, for example, a trihydrocarbyl or tridihydrocarbylamino phosphine such as a trialkylphosphine, and metallized metallic and nonmetallic substrates prepared therefrom.

United States Patent Earle M. Potralke Wilmington, Del.

Apr. 14, 1969 Dec. 7, 1971 E. 1. du Pont de Nemours and CompanyWilmington, Del.

Continuation-impart of application Ser. No. 540,517, Apr. 6, 1966, nowPatent No. 3,438,805, dated Apr. 15, 1969. This application Apr. 14,1969, Ser. No.

inventor Appl. No. Filed Patented Assignee SUPPORTED METALSALT/PHOSPHINE COMPLEXES AND METALLIZED PRODUCTS THEREFROM OTHERREFERENCES Jensen et al., Acta Chemica Scand. 3 (1949) 474- 480 PrimaryExaminerRalph S. Kendall Attorney-Louis H. Rombach ABSTRACT: Metalsalt/phosphine complexes deposited within and/or on a metallic ornonmetallic support or substrate, said complexes being derived from onemole of a nonorganometallic salt of a normally solid heavy metal of theDeming Periodic Table, for example, gold or palladium chloride, and l to4 moles of a triorganophosphine, for example, a trihydrocarbyl ortridihydrocarbylamino phosphinc such as a trialkylphosphine, andmetallized metallic and nonmetallic substrates prepared therefrom.

SUPPORTED METAL SALT/PHOSPHINE COMPLEXES AND METALLIZEDPRODUCTSTHEREFROM CROSSREFERENCE TO RELATED APPLICATION This is acontinuation-in-part of copending application Ser. No. 540,517 filedApr. 6, 1966 and issued Apr. 15, 1969 as US. Pat. No. 3,438,805.

Metal-coated articles are presently enjoying wide utility. They areoften conveniently obtained by chemical or nonelectroyltic methods,starting with a compound of the coating metal and converting it to themetal under controlled conditions. In general, however, the knownmethods are not entirely satisfactory; they each have one or moredisadvantages such as requiring exceedingly high temperatures orpreformed organometallic compounds, or are limited to aqueous platingbaths or to the use of active metal substrates in accordance with theelectromotive series, or are otherwise not readily adapted to plating awide variety of substrates. Of particular interest at the present timeis the coating of nonmetallic substrates such as plastics.

[t is an object of this invention to provide supported metalsalt/phosphine complexes which are useful in a variety of applications,including the preparation of metallized metallic nonmetallic substrates.A further object is to provide a method for producing said supportedcomplexes by depositing the complex within and/or on either a metallicor a nonmetallic substrate. A still further object is to providemetallized metallic or nonmetallic substrates.

It has now been discovered that a wide variety of substrates can bechemically metallized by the process which comprised heating a metalsalt/phosphine complex derived from 1 mole of a nonorganometallic saltof a normally solid heavy metal of the Deming Periodic Table and about 1to 4 moles of a trimgano phosphine in which each organo group is ahydrocarbyl or dihydrocarbylamino radical in the presence of thesubstrate to be metallized at a temperature of about 25 to 350 C., butbelow the decomposition temperature of the substrate and the heavy metalsalt alone, provided that when the substrate is not a heavy metal of theDeming Periodic Table other then the plating metal, the metalsalt/phosphine complex is in substantially pure form in direct contactwith the substrate. By metallized" is meant metal coated or metalimpregnated. By normally solid heavy metals is meant heavy metals whichare solid at nonnal ambient temperatures, thereby excluding metals suchas Hg and Ga which are liquid at temperatures as low as about 30 C. Byplating metal is meant the heavy metal of the salt from which thecomplex is derived. By substantially pure form is meant undiluted by anysubstantial amount of solvent, diluent or carrier. Minor amounts ofimpurities and additives are readily tolerated.

When the substrate is a normally solid heavy metal of the DemingPeriodic Table other than the plating metal, the substrate may beimmersed in a bath containing the metal salt/phosphine complex dissolvedin an inert solvent and the bath is heated for a time sufiicient toprovide an adherent coating of the plating metal on the substrate.

When the substrate is not a heavy metal of the Deming Periodic Tableother than the plating metal, the metal salt/phospine complex is heatedin substantially pure form in direct contact with the substrate. Whendirect contact between the complex is substantially pure form and thesubstrate is required, it is most conveniently provided by coating thesubstrate with the complex alone, especially in the case of a liquidcomplex, or by mixing the complex with a volatile carrier such as asolvent or diluent, coating the substrate with the mixture, evaporatingthe volatile carrier and heating the coated substrate, therebymetallizing the substrate.

Because the metal salt/phosphine complexes are soluble in a wide varietyof solvents, metal impregnates as well as coatings can be produced witha wide variety of polymeric substrates that are also soluble in suchsolvents and can be recovered and reconstituted by solvent evaporation.For impregnating a substrate such as plastic the metal salt/phosphinecomplex and a soluble polymer are dissolved in a mutual inert volatilesolvent, the solvent is evaporated to form an intimate metalsalt/phosphine-polymer mixture which is heated to produce theimpregnated plastic. A solvent is chosen which softens, swells ordissolves the plastic substrate thereby allowing the plating componentsto penetrate the surface or to become completely and intimatelyassociated therewith. Solutions of the metal salt/phosphine complex andthe substrate polymer can be cast as films, spun into fibers or moldedinto any desired shape and, with evaporation of the solvent and heating,converted into a metallized product.

Broadly, the method of this invention comprises heating the metalsalt/phosphine complex in the presence of the substrate to be metallizedat the temperature required to effect the metal salt/phosphine to metaltransformation in the particular case. The required temperature, whichmay be as high as 350 C., but usually is in the range of 25 to 250 C.,is significantly lower than that required to decompose the metal saltalone to the free metal.

When the substrate is a normally solid heavy metal of the DemingPeriodic Table other than the plating metal, plating temperaturesgenerally range from about 25 to 150 C. When the substrate is other thanthe specified heavy metals, somewhat higher temperatures in the range ofabout to 250 C. are generally required. In other words, metal platingwith the same metal salt/phosphine complex may require differenttemperatures depending depending whether upon not the substrate is oneof the specified heavy metals.

While the exact nature of this phenomenon is not definitely known, it isbelieved that the specified heavy metals may enter into an exchangereaction with the heavy metal of the complex. Although it is notintended that this invention be limited to any particular theory, theseexchange reactions could account for the lower temperatures encounteredwith heavy metal substrates.

However, these exchange reactions do not follow the normal relationshipsencountered in the electromotive series of the metals as shown forexample by Lange in Handbook of Chemistry, 10 the Edition, page 1,218,McGraw-Hill Book Co. In accordance with this invention, metals such asaluminum, manganese, zinc, chromium, iron, cobalt, nickel and tin arereadily plated on a substrate such as copper, which is lower down in theelectromotive series than these plating metals. Such exchange reactionsare contrary to the accepted rules of the electromotive series.

It is possible that the presence of the phosphine in the complex mayalter the normal forces in the electromotive series. It has been foundthat by proper selection of the phosphine and solvent, any of the heavymetals can be plated on any other heavy metal at substantially reducedtemperatures.

The complexes used in accordance with this invention are derived in partfrom salts of the normally solid heavy metals of the Deming PeriodicTable. These heavy metals are defined in the Deming Periodic Table asshown by H. G. Deming in F undamental Chemistry, 2nd Edition (1947),page 255, John Wiley & Sons, Inc. and by Lange in Handbook of CHemistry,10th Edition, pages 56 and 57. Suitable heavy metals which may be usedin accordance with this invention include: Cu, Ag and Au (Group I B);Znand Cd (Group 11 B); A1, TI and In (Group 111); Sn, Pb, Ti and Zr (GroupIV); Sb, V, Nb, Ta and Bi (Group V); Cr, Mo and W (Group Vl); Mn and Re(Group Vll;); Fe, Ru, Co, Rh, Ni, Pd, Pt, Os and Ir (Group VIII).

The heavy metal salts from which the metal salt/phosphine complexes arederived are nonorganometallic salts. By nonorganometallic salt" is meanta salt which is free of carhon-metal bonds. In other words, thisinvention is directed to the utilization of heavy metal compounds intheir commonly available, essentially inorganic salt forms and does notrequire that the metal salts first be activated by conversion to anintermediary organometallic form. The heavy metals are commonlyavailable and conveniently used as the chlorides, bromides, iodides,cyanides, nitrites, nitrates, perchlorates, fluoroborates, carbonates orcarboxylates such as acetates and trifiuoroacetates.

Preferred plating metals are the ductile, noble and precious metals ofGroups I B, and VIII, especially the salts of silver, copper, gold,nickel, cobalt, palladium and platinum. Still other preferred platingmetals are titanium, chromium, zinc and tin. These are preferablyemployed as the readily available chlorides, bromides and iodides, butsometimes, as in the case of silver, are more advantageously used as thenitrites, nitrates or perchlorates.

The complexes are also derived in part from triorgano phosphines inwhich each organo group is a hydrocarbyl or dihydrocarbylamino radical.Each of the hydrocarbyl groups, including those in thedihydrocarbylamino radical, may be aliphatic, cycloaliphatic or aromaticand, for reasons of availability and economy, normally contain fromabout one to carbon atoms, but may contain up to about 18 carbon atoms.These groups may be straight-chain, branchedchain, saturated orunsaturated including ethylenic and acetylenic unsaturation.Exemplifying such groups are methyl, ethyl, npropyl, isopropyl, n-butyl,isobutyl, sec-butyl, tert-butyl, amyl, hexyl, octyl, decyl, dodecyl,hexadecyl, octadecyl, propenyl, allyl, butenyl, propargyl, octadecenyl,cyclopentyl, cyclohexyl, cyclohexenyl, phenyl, totyl, xylyl,ethylphenyl, styryl and dodecylphenyl. The trialkyl phosphines arepreferred, particularly the tri-lower alkyl phosphines having from aboutone to five carbon atoms in each alkyl group.

The hydrocarbyl secondary amino groups are preferably, for reasons ofavailability and economy, di-lower alkylamino groups where each alkylhas from about one to five carbon atoms such as dimethylamino,diethylamino, methylethylamino,'dibutylamino, methyl amylamino anddiamylamino. Suitable homologs and analogs include dioctylamino, methyloctadecylarnino, ethyloctadecenylamino, methyl cyclopentylamino, methylcyclohexylamino, octyl cyclohexylamino, dicyclohexylamino,N-methylanilino, N- ethylanilino and N-methyl toluidino. The hydrocarbylgroup may also constitute a single divalent radical such as thepyrrolidino and piperidino radicals.

The process of this invention may be carried out using a preformed metalsalt/phosphine complex, or the complex may be prepared in situ by addingthe metal salt and phosphine separately to a solvent in which thecomplex is soluble. In either case, the complex is formed and acts as anecessary component in the process. When the complex is formed in situsmall excesses of metal salt or phosphine may be present. These do notinterfere with the metallization process.

As is well known in the art, phosphines and heavy metal salts generallyform definite coordination complexes involving from 1 to 4 moles of thephosphine per mole of the salt. For efficient utilization of the heavymetal salt in forming the complex in situ, the phosphine is normallypresent in amounts corresponding to at least about I mole per mole ofheavy metal salt. More than about 4 moles of the phosphine per mole ofsalt is generally not needed, but may be used, if desired. The optimumamount of the phosphine may vary depending on the particular heavy metalsalt and the substrate to be coated. Usually, however, only about 2moles of the phosphine are needed per mole of salt and sometimes onlyabout 1, particularly in the case of Group I B metals. The formation ofdefinite metal salt/phosphine complexes constitutes an importantpractical advantage since the complexes are easily obtained pure and canbe conveniently stored and handled at ordinary temperatures.

In general the metal salt/phosphine complexes decompose to form metal ator slightly above their melting points and in general this is completedat temperatures below about 350 C. As a class, the triaryl phosphinecomplexes are thermally more stable than the trialkyl phosphinecomplexes and require higher metallization temperatures. This may beadvantageously used where enhanced thermal stability of a complex isneeded as in controlled and stepwise metal deposition. Thus, the widevariety of phosphines that are available enables one to control or. varythe temperature of metallization to suit the particular processing need.

The metal salt/phosphine complexes, in contrast to the metal salts fromwhich they are derived, are highly soluble in a wide variety of organicsolvents making possible the formulation of a wide range of platingcompositions. The solvent of course should be substantially inert to theplating ingredients and the substrate. Suitable solvents includealcohols such as methanol, ethanol, 2-propanol and 2-methyl-l-propanol;ethers such as diethyl ether, furan, tetrahydrofuran and dioxane;ketones such as acetone and methyl ethyl ketone; hydrocarbons such aspentane, hexane, isooctane, tetradecane, benzene, xylene and toluene;halogenated hydrocarbons such as chloroform, methylene chloride, carbontetrachloride, chlorobenzene, dichlorobenzene, trichloroethylene, l, l,2,2-tetrachlorol ,2-difluoroethane, l l ,2-trichloro-l,2,2-trifluoroethane, trichlorofluoromethane, chlorotrifluoromethane andmixtures and azeotropes thereof; nitriles such as acetonitrile,butyronitrile and benzonitrile; amines such as triethylamine,tributylamine, pryridine and picoline; amides such as dimethylformamide,dimethylacetamide, hexamethylphosphoramide and hexaethylphosphoramide;and esters such as ethyl acetate, butyl acetate and amyl acetate.

The main function of the solvent is to provide liquid, easily handledcompositions which can effectively bring the metal salt/phosphinecomplex in intimate contact with the substrate to be metallized. Thesolvent may also serve to transfer heat to the metallizing componentsand as a vehicle for other ingredients having beneficial effects such asplating promoters and surface conditioners. Volatile solvents arepreferred, particularly those which can be evaporated from themetallizing compositions at temperatures at or below the temperature atwhich metallization occurs.

The method of this invention can be applied to a wide variety ofsubstrates, including metallic and nonmetallic materials. The metals maybe any of those normally used for decorative, structural or electricalpurposes. These are usually the normally solid heavy metals of theDeming Periodic Table and alloys thereof. For practical reasons thesubstrate metal is generally different from the plating metal exceptwhere special effects such as relief are desired. Besides the heavymetals, other metals may alsoserve as substrates including the rareearths such as cerium and actinides such as uranium. As pointed outabove the substrate metal may be higher or lower than the plating metalin the electromotive series of the metals.

There may also be used as substrates siliceous solids such as glass,Pyrex glass, spun glass, and asbestos; carbonaceous materials such asgraphite and the various amorphous carbon blacks; refractory materialssuch as carborundum, ceramics and cermets; natural and syntheticcellulosic materials such as cotton, hemp, jute, paper, parchment, wood,cellulose acetate, and rayon; proteineous materials such as silk, wool,leather, mohair and fur. Still other important substrates are thesynthetic polymeric compositions exemplified by the polyvinyls such aspolyacrylonitrile, polyvinyl chloride, polytrifluorochloroethylene,polytetrafluoroethylene, polystyrene, polyethylene, polypropylene,polyvinyl acetate, polyvinylidene fluoride, poly(alkyl methacyclates)and copolymers thereof; polybutadiene, poly(diallyl esters) such aspoly(diallyl phthalate); polyamides such as nylon, polyimides,polyesters, polyurethanes, polyacetals, melamine-formaldehyde,ureaformaldehyde, phenol-formaldehyde and epoxies. When the substrate isa polymeric material, the metallization temperature should be below thedeformation temperature of the polymer.

The substrate may be particulate, for example powdered, or it may have acontinuous surface in the form of a sheet, film, tape, foil, wire,fiber, fabric or foam. It may be a highly surface-porous mass which isto be impregnated and coated at the same time such as a porous catalystsupport.

As is well known in the plating art, for best results the substrate tobe plated should be clean especially with respect to grease and loosescale. Any of the known techniques may be l n I n I 1 Anna used toprepare the surface to be plated. For example, metal surfaces can betreated as described by Burns and Bradley in Protective Coatings forMetals, 2nd Edition, Chapter 2, Reinhold Publishing Corporation. Plasticsurfaces can also be preconditioned according to known techniques. Forexample, the surface can be mechanically satinized" as described byBruner and Baranano in Modern Plastics, Dec., l96l, and in Chemical andEngineering News, Mar. 25, 1963, pages 48 and 49. Or the surfaces may bechemically etched, as in the case of polyfluoroethylene being treatedwith an alkali metal-amine solution as described in Canadian Pat. No.653,304, or with an alkali metal-aromatic ether solution as described inU.S. Pat. No. 2,809,130.

It is often beneficial to condition the surfaces to be plated,especially metal surfaces, with conditioners such as the commonlyemployed hydrohalic acids including hydrochloric, hydrobromic,hydrofluoric and hydroiodic acids or sulfuric acid, or by treating witha small amount of an inorganic reducing salt such as stannous chloride.Such promoters may be incorporated directly into the metalsalt/phosphine plating composition of this invention, if desired.Conveniently this may be done in a carrier solvent, especially alcoholssuch as methyl, ethyl and propyl alcohols.

As an improvement within the scope of this invention, it has beendiscovered by other inventors that for many of the metal salt/phosphinecomplexes, especially those derived from the noble metals, thetemperature or time required for metallization in accordance with thisinvention can be further reduced by sensitizing the metal salt/phosphinecomplex to subsequent thermal treatment. Sensitization may beaccomplished by incorporating into the metal salt/phosphine complexplating composition a thermally dissociable free radical generator suchas carbon tetrabromide or an organic perioxide, or by irradiating thecomplex with ultraviolet light, or exposing it to an electron beam orcontacting it with a spark discharge. By these techniques thetemperature requirement can be reduced by as much as 100 C. for platingon nonmetallic substrates. The sensitizing step is particularlyadvantageous in the case of heat sensitive substrates such as certainplastics. This improvement allows the use of a wider variety ofcomplexes with these substrates.

The following examples, illustrating the novel method disclosed hereinfor metallizing a wide variety of substrates, are given without anyintention that the invention be limited thereto. In these examples, allparts and percentages are by weight unless otherwise specified;solutions of metal salt/phosphine complexes, where employed, wereprepared and used in nonmetallic (usually glass) containers; and metalsto be plated were in the form of 1X1X% in. coupons unless other wisenoted. Prefomied metal salt/phosphine complexes, where used, wereprepared by known methods. Adherence of the metal coatings to thesubstrate was measured by the Scotch tape croshatch test.

A. GROUP I B PLATING Examples 1 to IS A gold-plating stock solution wasprepared by dissolving 1 part of (CH P-AuCl in 80 parts of 95 percentethanol containing 5 parts of added concentrated hydrochloric acid.Aliquots were used to plate immersed test coupons of various metals byheating at 80 C. for the time indicated in the table below.

TABLE I Example Substrate Time, hours aluminum antimony bismuth cadmiumcobah 6 copper lead 8 nickel 9 platinum l0 SILVER 1 l stainless steel 12thallium l3 tin tungsten broke -neon or TABLE I1 Example Substrate Time,hours No. 2 carbon steel Hastelloy B lead 400 Monel nickel Ni-O'Nel 309stainless steel 405 stainless steel 4l0 stainless steel 430 stainlesssteel A-bMMNNnu-w Example 26 Using the procedure described in examples Ito 15, a solution containing 1 part of (Cl-l P'AuCl, parts of percentethanol and 1 part of concentrated hydrochloric acid was used to plate 2parts of 200-mesh powdered copper, by heating at 80 C. for 2 hours. Thepowdered copper was uniformly gold plated as evidenced by examinationunder a microscope. Example 27 The procedure of example 26 was repeatedusing 200-mesh powdered nickel as the substrate with the same result.Example 28 The procedure of example 26 was repeated using 200-meshpowdered stainless steel as the substrate with the same result. Example29 A plating solution containing 1 part of (CH P-AuCl, 200 parts ofethanol and 3 parts of concentrated hydrochloric acid was prepared. A316 stainless steel coupon was placed in the solution of 2 hours atboiling. An adherent gold coating was produced on the 316 stainlesssteel. Example 30 The procedure of example 29 was repeated except that200 parts of 2-propanol were substituted for the ethanol with the sameresult. Example 31 were The procedure of example 29 was repeated exceptthat 200 parts of 2-methyl-l-propanol was substituted for the ethanolwith the same result. Example 32 The procedure of example 29 wasrepeated except that 200 parts of acetone were substituted for theethanol with the same result. Example 33 The procedure of example 29 wasrepeated except that 200 parts of chloroform were substituted for theethanol with the same result. Examples 34 to 41 Using the procedure ofexamples 1 to 15 various gold-plating compositions were used toadherently plate various metallic substrates under the conditionsindicated in the table below.

sis III Temp., Time, Ex. Plating solution, parts G. hrs. Substrate 1 pt.(CH3); P-AuCl- 84 80 pts. 95% ethanoL 80 1 Bronze.

i3 pts.(gorI11c.)fBi .61 p 4 9 s l1 35 '{250 pts. acetonltrile U} 80 6Copper 1 pt. (CuHs)a-PAI1C1 36 100 pts. dimethyliormamlde. 100 0. 1 Mildsteel.

20 pts. acetic acid. 1 pt. (CHmP-AuL 37 160 pts. methanol 60 0. 5Niobium.

1 pt. cone. HF 1 pt. (CHa)aP-A11I 38 o1 60 1 Aluminum.

39 60 1. 5 Uranium.

1 pt. (CH3)3PA11I 40 160 pts. acetone. 50 1. 5 Aluminum.

pt. cone. HI- 41 {1 pt. (CsHs)aP-Au 80 1 Stainless 250 pts. 95% ethanolsteel.

Example 42 Silver-plating compositions, prepared by dissolving 1 part of(Cl-1 );,PAgl in 250 parts of 2-propanol, and adding 0.5 part ofconcentrated hydrochloride acid, produced lustrous, adherent silverplates on brass coupons immersed in the boiling solution for 0.5 hour.

Example 43 The procedure of example 42 was repeated using 250 parts oftriethylamine in place of the 2propanol with the .same result.

Example 44 The procedure of example 42 was repeated using 250 parts ofacetone in place of the 2-propanol with the same result. Example 45 Theprocedure of example 42 was repeated using 250 parts of acetonitrile inplace of the 2-propanol with the same result. Examples 46 to 51 Varioussilver-plating compositions were used in the procedure of examples 1 to15 to produce lustrous adherent silver plates on various substratesunder the conditions indicated in the table below.

'riiia'iia n if Temp., Time, Ex. Plating composition, parts 0. hrs.Substrate 46 {1 pt. (CHmP-AgI 50 2.5 Phosphor 20 pts. acetone bronze.

1 pt. (CHmP-AgI 50 3 Copper (200 47- 16 pts. acetone mesh) powder. 1 pt.[(CsHQgPlrAgNOa 80 1 Everdur" 48.-. 16 pts. 95% methanoL Cfil-Sl-Mn a y.1 pt. [(CaHt)2CH:P] -AgN0a 49"- 40 i ggg i g d so 0. 2 Copper.

1 pt. 3 3 gN 50 wh (C 1:1, 6 so 0.2 Do.

1 p 0 n a Z 8N "{125 pts. acetonitrile 80 2 Examples 52 to 55 Variouscopper salt/phosphine complexes were used in the procedure of examples 1to 15 to produce lustrous, adherent copper plates on various substratesunder the conditions indicated in th tabls slswt, V ,7 V ,7 .7

TABLE v Time,

Temp.,

C hrs.

Ex. Plating solution, parts Substrate {1 pt. [(CtHQaPCllClZ n} 52- 100pts, dimethyltormamide O. 3 Mild steel,

00 pts. 95% ethanol... 80 2 Brass.

pts. conc. HCl. {1 pt. on-mar uOC(O)CH 100 pts. acetonitrile 3 GoldExample 56 The liquid complex, (C,H,,);,P-AuCl, was spread on a siliconwafer which was then-heated on a 180C. hot plate. Within 5 minutes, thewafer had become coated with an adherent, electrically conductive goldlayer. When cooled, the resistance of the wafer was less than 0.5 ohm/cmor less than 1/ 1,000 of the original resistance.

It will be apparent to those skilled in the solid-state electronics artthat this process and the gold-coated silicon produced thereby areuseful for preparing integrated microcircuits.

Example 57 A 0.1 percent solution of (Cl-l hP-AgNo in acetone was spreadover a 1X1 in. film of polytetrafluoroethylene whose surface previouslyhad been treated with a sodiumnaphthaJene-tetrahydrofuran solutionessentially as disclosed in US. Pat. No. 2,809,120. After the acetonehad evaporated, the film was placed with the coated side up on a C. hotplate while the coated side was simultaneously heated with a hot airstream from a commercial hair dryer at a somewhat lower temperature. Abright silver coating appeared almost immediately. The silver coatingwas flexible, adherent, had a resistance of about 10 ohm/cm, and couldbe wiped with a paper towel to a mirror-bright finish. Rubbing andcornpressing the coating with a spatula further improved its luster andconductivity.

Example 58 Example 57 was repeated on a film of Delrin polyacetal resinthat had previously been satinized as described by Bruner and Barananoin Modern Plastics, Dec. 1961. Simply heating on a hot plate at C. for15 minutes produced a lustrous, flexible, adherent and electricallyconductive silver coating on the film.

Example 59 The procedure of example 58 was repeated except that anuntreated Zytel polyamide resin film was used as the substrate withessentially the same result.

Example 60 The procedure of example 58 was repeated except that anuntreated Mylar polyester film was used as the substrate withessentially the same result.

Example 61 The procedure of example 58 was repeated except that anuntreated Kapton type H polyimide film was used as the substrate withessentially the same result.

Example 62 A solution containing 1 part of (Ce,,ll,),CH,P-AgNO,, 1 partof a filmfonning vinylidene fluoride/tetrafluoroethylene copolymer and 4parts of acetone was cast as a film on aluminum foil. The acetone wasevaporated and the coated piece heated at C. for 5 minutes to develop aflexible, silvery coating which was adherent to the aluminum foil.

Example 63 The procedure of example 62 was repeated except that a glassplate was used in place of the aluminum foil with the same result. Themetal-impregnated coating adhered to the glass.

Example 64 A piece of Torvex ceramic honeycomb (4 in. in diameter, 1 in.thick and having a three-sixteenths in. pore size) was dipped into oneliter of a 1 percent solution of (CH P- AgNO, in acetonitrile, air-driedto evaporate the acetonitrile, and subjected a stream of hot air from ahot-air gun at approximately 200 C. to develop a silvery coating. Theprocedure was repeated eight times to build up a continuous silvercoating throughout the porous structure.

Such product, presenting a large silver surface, but with its openhoneycomb structure substantially unchanged so that gas flowing throughit remains substantially unimpeded, is useful as a silver catalyst invapor-phase reactions.

.13.: ELA QW THQRQU 1 B METALS Examples 65 to 71 Metal coupons to beplated, 1X1 .5 in., were immersed in liquid plating compositions,consisting of 1 part of a bis(trialkylphosphine) metal halide dilutedwith about 2.5 parts of an inert solvent as specified in the tablebelow. The coupons were held in the baths for the times and at thetemperatures noted in the table below, removed, rinsed with water andacetone, and inspected. I

Examples 82 to 88 Metal plates were produced on copper test coupons withYellow metal substrates were chosen for these tests so that 5 theplating compositions specified in the table below which the formation ofsilvery-white metal coatings would be readily apparent on visualinspection. All coatings were adherent.

were prepared as in examples 75 to 81. Heating was l6 hours at 100 C.except in the case of example 88 which was for 12 v Temp, Time, ExamplePlating composition 0. hrs. Substrate Result 65(CHi)3P]:-ZnBrz+dlrnethyli'ormamide 100 0.5 Copper. Zn coating; 66.(C4Ho)iPlr-Zn(OC(0)0H,),+dlmethylformamide. 25 24 Brass. Do. 67.((CH;)|N) P]|-ZnCli+hexamethylphosphoramlde. 100 24 Cop er. Heavy Zncoating. 68. [((CHs)2N)3P]:ZnI +hexamethylphosphoramide. 100 24 m Do.69. [(C4HmPh-Cd0h+tetradecane 150 0.5 .do....... Lustrous Cd plating. V

C. PLATlNG WITH GROUP lll METALS hours. Plating in examples 82 to 84 wasconfirmed by X-ray p 7 emission and fluorescentm spectra of thecoatings.

Aluminum was plated on copper by heating a copper test 25 TABLE V IIIcoupon at 35 C(for 6 hours in a plating solution prepared by P1 n tadding 20 g. of triphenylphosphine (0.076 mole) in 100 ml. of a g etherto a filtered solution containing 5 g. of anhydrous AlCl Example salt{gigg solvent (0.038 mole) lll l00 ml. of ether and removing the smallamount of oil that separated. 82 figf Example7l B t l T Do.

Thallium was plated on copper by heating a copper test cou- T 01 f y ponin a solution containing 2.6 g. of TlOC(O)CH (0.01 '87 Niels 3l o.K.?T-?III l io. mole) and 4.1 g. of tributylphosphine (0.02 mole) in 50 ml.of Ebola 'f Hexamemyphmphommme' toluene for 16 hours at 100 C. Example72 F. PLATING WITH GROUP VI METALS lndium was heavily deposited on agold coupon by heating ,Examples 89 to 92 the gold coupon in a solutioncontaining 2.2 g. of lnCl, (0.01

mole) and 8.l g. of tributylphosphine (0.04 mole) in 50 ml. of 4acetonitrile for 3 hours at 80 C.

D. PLATING WITH GROUP IV METALS The procedure of example 73 was repeatedexcept that a silver test coupon was used in place of copper with thesame result. Examples 75 to 8l Metal plates were obtained by immersing asubstrate in a plating composition and heating for 16 hours under theconditions summarized in the table below. The plating compositions wereprepared by mixing approximately 2.2 molar proportions of a phosphine, amolar proportion of a Group W B metal salt and optionally about 10 partsof a diluent per part of metal salt. Visual inspection and, wheretaken", the X-ray fluorescence or emission spectrum of each resultingtest piece shown a Group IV B metallic coating on its surface.

Metal plates were produced on copper test coupons with 0 the platingcompositions specified in the table below which were prepared as inexamples to 81. Heating was 16 hours at l00 C. X-ray emissionspectroscopy confirmed that the example 91 plate was chromium.

Following the procedure of examples 75 to 81, amanganese coating,confirmed by X-ray emission spectroscopy, was plated on copper byheating a test coupon in a (CH;)',N] ,P- MnCl, hexamethylphosphoramidesolution for l2 hours at [50 C.

u. PLATING WITH 0110p Vlll METALS Examples 94 to 103 The procedurefollowed was e ssentially that described for examples 75 to 81, exceptthat the plating compositions and MX -R P was added directly to theplating solvent. In all cases the coatings were adherent.

piece of wood was used in place of the glass slide with substantiallythe same result. Example 1 The procedure of example 107 was repeatedexcept that a carbon sheet was used in place of the glass slide withsubstanie!!! lh'PFPE-EQUH V.

TABLE X Plating composition Phos hine Temp Time, Example Salt RiP,Solvent hrs. Substrate Result MezN Hexamethylphosphoramlden 150 12 Fecoat. Butyl Acetonitrlle 80 3 Co coat. MezN.. Hexamethylphosphoramide150 12 Rh t, Phenyl. 83% acetonitrlle, 17% acetic acld 80 1 Bright N1coat. Butyl Acetic acid 100 3. 5 Lustrous N1 coat. o... -..do 100 2 Do.Methyl 95% ethanol 5% cone. H01 70 2 Ni oat, 101..."... PdCl: .d0 95%ethanol 5% cone. H01....... 70 1 Lustrou Pd coat. 102 Ptcl, do 95%ethanol trace HF 70 7 Copper Lustrous P1;

103 Pm do 95% ethanol trace HF 70 7 Pt mm Example 104 About I g. offinely powdered [(CH:,);,P],'PdCl was spread on a 2 mil. thick, 3X3 in.square of a high-temperature resistant Kapton type H polyimide film. Thecoated film was gradually heated on a hot plate under a nitrogenatmosphere- I. EXAMPLES ILLUSTRATING IMPROVEMENTS WITHIN THE SCOPE OFTHIS INVENTION Example 105 One part of (CH P-AuCl was dissolved in 25parts of a percent solution of Orlon polyacrylonitrile indimethylformamide. The solution was spread on a glass microscope slideand warmed with a heat lamp to evaporate the dimethylformamide. Theslide was then exposed to a Tesla coil spark discharge to sensitize thegold salt complex to thermal decomposition and placed treated-side up ona 200 C. hot plate for about 5 minutes. The resulting uniformlydistributed golden coating was adherent to the glass and electricallyconductive. Example 106 A (CH P-AuCl/polyacrylonitrile/dimethylfonnamidesolution, substantially as described in example 105, was spread on aglass side and the dimethylformamide evaporated by warming under a heatlamp. The resulting film was then covered with a stencil, irradiatedwith high intensity light by contact flashing with a 200 watt-secondxenon flash tube (Hico lite, Model K; 1 millisecond duration flash),then heated at 100 C. for aboutS minutes. The resulting slide showed alustrous, electrically conductive, adherent golden image correspondingto the irradiated areas. Example 107 Example 105 was repeated with 1part of (CH P-AuCI per 5 parts of poly[4,4'(hexafluoroispropylidene)diphenol isophthalate] polyester as the carriersubstrate in 100 parts of methylene chloride. The resulting film, afterhaving been exposed to the spark discharge and heated at 200 C. for 2minutes, was golden, adherent and electrically conductive.

Such products are useful in printed circuitry for use at elevatedtemperatures. Example 108 The procedure of example 107 was repeatedexcept that a piece of porcelain was used in place of the glass slidewith substantially the same result. Example 109 The procedure of example107 was repeated except that a The procedure of example 107 was repeatedexcept that a piece of ceramic was used in place of the glass slide withsubstantially the same result.

Example 112 Repeating example 107 with 0.5 part of the gold complexproduced uniformly colored purple slides, indicating colloidal golddispersed throughout the polymeric film, which were useful asinterference filters.

Example 113 A mixture of I part of (CH P-AgNO and 70 parts offilmforming polyvinylchloride, cast as a film on glass fromdimethylformamide solution, was irradiated three times through a stencilwith the light source described in example 106 and then heated to 180 C.for 5 minutes to develop a silvery image. The silver deposit was muchless noticeable in the unirradiated area.

Example 114 The procedure of example 113 was repeated except that 1 partof (C,,l'I,,) P-AgClO was used as the silver complex with the sameresult.

Example 115 The procedure of example 113 was repeated except that 1 partof (C I-I P-Ag0C(O)CH was used as the silver complex with the sameresult.

Example 116 The procedure of example 113 was repeated except that 1 partof (C H P-AgI was used as the silver complex with the same result.

Example 117 The procedure of example 1 13 was repeated except that 1part of (C,;H P-AgOC(O)CF was used as the silver complex with the sameresult.

Example 118 The procedure of example 113 was repeated except that 1 partof [(C H P] 'Ag C0,- was used as the silver complex with the sameresult.

Example 119 The procedure of example 113 was repeated except that 1 partof (C H,,) P'AgCN was used as the silver complex with the same result.

Example 120 The procedure of example repeated except that l Thus, itshould be apparent from the above examples that this invention has wideutility. It is useful to produce metallized objects having continuous,adherent and, where needed, flexible, electrically conductive metalcoatings. For example, it is useful to produce (1) metallic coatingsthat protect the underlying material and that reflect light and infraredradiation; (2) electrically conductive articles such as printedcircuits, resistors, capacitors, and electrodes for fuel cells andbatteries; (3) various decorative pieces (e.g., automotive hardware),effects, and images based on the formation of metal surfaces; (4) newcatalyst structures wherein a catalytically active heavy metal isimpregnated and coated on a porous substrate carrier; and (5) metallizedfilms showing selective light transmission which can be used as opticalfilters. It is also useful to obtain coatings of the normally brittlemetals such as titanium, zirconium, chromium, vanadium, niobium, andmanganese which are difficult to obtain by other methods. It is alsouseful to produce metallized plastics wherein the metal is uniformlydistributed throughout the body of the plastic as well as on itssurface. This is of great practical advantage when the surface of theplastic is normally subjected to abrasion.

In addition to their uses as intermediates for producing metallizedproducts having wide utility as described above, the metalsalt/phosphine/substrate compositions can also be used as temperatureindicators and time-temperature integrators, recording by metaldeposition the degree of exposure of the supported material when certaincharacteristic temperatures (threshold temperatures for metallization)have been reached and exceeded. The metal salt/phosphine/substratecompositions also have wide utility in their premetallized state,wherein the supporting substrate functions as a carrier, a reactionmedium or a means for facilitating chemical reactions of the metalsalt/phosphine complexes; they may afford advantages over thecorresponding unsupported metal salt/phosphine complexes; such asdisclosed in US. Pat. No. 3,045,775 and British Pat. No. 714,202.

The complexes represent higher oxidation states of the metal moiety withrespect to lower valent, including zero valent, states of the metal andthus are useful broadly as oxidin'ng agents or electron acceptors. Thetransition metals are variable-valent and in some of the complexesincluded herein, for example [C,H P] RhCl and [[(CH ),N],PtCl P]FeCl,,are in lower valent states; thus the supported materials can function aselectron-donating or reducing agents towards a proper electron acceptor.The potentials, or the ability of a particular supported complex toefiect oxidations or reductions, can be determined by standard methodsand related to reference electrodes. The potentials will vary with theparticular phosphines and the other ligands, and the number thereof,which are coordinated to the central metal atom.

Supported transition metal salt/phosphine complexes can further complexwith ethylene and other donor-acceptor ligands and can be used toseparate olefins from nonolefins and to fonn olefin complexes'forfurther reaction of the bound ligands. For example, supported complexessuch as H );,P] RuCl,, [(C,H P],RhC1 and [(C,,l-l P] PtCl -SnC] can beused to catalyze olefin and nitrobody hydrogenations. Supportedcomplexes of trialkyl or triaryl phosphines, for example, tributyl ortriphenyl phosphine, and metal halides such as nickel, palladium orplatinum chlorides or bromides can be used to decarbonylate aldehydes tohydrocarbons and carboxylic acid chlorides to chlorohydrocarbons.Supported corn:

plexes of trialkyl and triaryl phosphines, as above, and chlorides orcobalt, palladium, platinum or rhodium can be used to catalyze doublebond migration in olefins, dimerization of olefins and polymerization ofdienes.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A supported metal salt/phosphine complex comprising a metallic ornonmetallic substrate coated or impregnated with a metal salt/phosphinecomplex, said complex being derived from one mole of a nonorganometallicsalt of a nonnally solid heavy metal of the Deming Periodic Table and lto 4 moles of a triorganophosphine in which each organo group ishydrocarbyl or dihydrocarbylamino.

2. The supported complex of claim 1 wherein the complex is a coating onthe substrate.

3. The supported complex of claim 1 wherein the heavy metal is atransition element, the triorganophosphine is a trihydrocarbylphosphineand the substrate is a nonmetallic substrate.

4. The supported complex of claim 3 wherein the transition element is aGroup [B or Group VIII element, the trihydrocarbylphosphine is atrialkylphosphine, and the nonmetallic substrate is a siliceous solid, acarbonaceous solid, a refractory material, a cellulosic material, aproteinaceous material or a polymeric material.

5. The supported complex of claim 4 wherein the salt is gold chloride,the trialkylphosphine is a tri-lower alkylphosphine, and the substrateis a polymeric material.

6. The supported complex of claim 4 wherein the salt is silver nitrite,the trialkylphosphine is a tri-lower alkylphosphine, and the substrateis a polymeric material.

7. The supported complex of claim 4 wherein the salt is palladiumchloride, the trialkylphosphine is a tri-lower alkylphosphine, and thesubstrate is a polymeric material.

8. The supported complex of claim 4 wherein the salt is silver nitrite,the trialkylphosphine is a tri-lower alkylphosphine, and the substrateis a porous ceramic body.

9. The supported complex of claim 4 wherein the nonmetallic substrate isa synthetic polymer and the complex is a coating on the substrate.

10. The supported complex of claim 4 wherein the nonmetallic substrateis a synthetic polymer and the complex is impregnated within thesubstrate.

11. A method for preparing a supported metal salt/phosphine complexwherein the complex is coated on a substrate, which method comprisescontacting a metallic or nonmetallic substrate and a volatile inertsolvent solution of a complex derived from one mole of anonorganometallic salt of a normally solid heavy metal of the DemingPeriodic Table and l to 4 moles of a triorganophosphine in which eachorgano group is hydrocarbyl or dihydrocarbylamino, and evaporating thevolatile inert solvent to produce a coated substrate.

12. A method for preparing a supported metal salt/phosphine complexwherein the complex is impregnated within a polymeric substrate, whichmethod comprises dissolving in a volatile inert solvent a polymer and acomplex derived from one mole of a nonorganometallic salt of a normallysolid heavy metal of the Deming Periodic Table and 1 to 4 moles of atriorganophosphine in which each organo group is hydrocarbyl ordihydrocarbylamino, and evaporating the volatile inert solvent toproduct an intimate salt/phosphine/polymer mixture.

Disclaimer 3,625,755.Earle M. Potmfke, Wilmington, Del. SUPPORTED METALSALT/PHOSPHINE COMPLEXES AND METALLIZED PRODUCTS THEREFROM. Patent datedDec. 7 1971. Disclaimer filed Aug. 20, 1970, by the assignee, E. du Pontde Nemours and Company.

Hereby disclaims all that portion of the term of the patent subsequentto Apr. 15,1986.

[Ofiicz'al Gazette September 12,1972]

2. The supported complex of claim 1 wherein the complex is a coating onthe substrate.
 3. The supported complex of claim 1 wherein the heavymetal is a transition element, the triorganophosphine is atrihydrocarbylphosphine and the substrate is a nonmetallic substrate. 4.The supported complex of claim 3 wherein the transition element is aGroup IB or Group VIII element, the trihydrocarbylphosphine is atrialkylphosphine, and the nonmetallic substrate is a siliceous solid, acarbonaceous solid, a refractory material, a cellulosic material, aproteinaceous material or a polymeric material.
 5. The supported complexof claim 4 wherein the salt is gold chloride, the trialkylphosphine is atri-lower alkylphosphine, and the substrate is a polymeric material. 6.The supported complex of claim 4 wherein the salt is silver nitrite, thetrialkylphosphine is a tri-lower alkylphosphine, and the substrate is apolymeric material.
 7. The supported complex of claim 4 wherein the saltis palladium chloride, the trialkylphosphine is a tri-loweralkylphosphine, and the substrate is a polymeric material.
 8. Thesupported complex of claim 4 wherein the salt is silver nitrite, thetrialkylphosphine is a tri-lower alkylphosphine, and the substrate is aporous ceramic body.
 9. The supported complex of claim 4 wherein thenonmetallic substrate is a synthetic polymer and the complex is acoating on the substrate.
 10. The supported complex of claim 4 whereinthe nonmetallic substrate is a synthetic polymer and the complex isimpregnated within the substrate.
 11. A method for preparing a supportedmetal salt/phosphine complex wherein the complex is coated on asubstrate, which method comprises contacting a metallic or nonmetallicsubstrate and a volatile inert solvent solution of a complex derivedfrom one mole of a nonorganometallic salt of a normally solid heavymetal of the Deming Periodic Table and 1 to 4 moles of atriorganophosphine in which each organo group is hydrocarbyl ordihydrocarbylamino, and evaporating the volatile inert solvent toproduce a coated substrate.
 12. A method for preparing a supported metalsalt/phosphine complex wherein the complex is impregnated within apolymeric substrate, which method comprises dissolving in a volatileinert solvent a polymer and a complex derived from one mole of anonorganometallic salt of a normally solid heavy metal of the DemingPeriodic Table and 1 to 4 moles of a triorganophosphine in which eachorgano group is hydrocarbyl or dihydrocarbylamino, and evaporating thevolatile inert solvent to product an intimate salt/phosphine/polymermixture.